<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        let weeks = prompt('请输入一个星期数')
        switch (weeks) {
            case '星期一':
                alert('monday')
                break
            case '星期二':
                alert('tuesday')
                break
            case '星期三':
                alert('wednesday')
                break
            case '星期四':
                alert('thursday')
                break
            case '星期五':
                alert('friday')
                break
        }
    </script>
</body>

</html>